1ST INTERNATIONAL SYMP ON DNA FINGERPRINTING location:Bern. Switzerland date:1-3 October 1991
Minisatellite or variable number of tandem repeat (VNTR) regions contain such a high degree of polymorphism that they allow one to construct an individual-specific DNA "fingerprint". Analysis of these sequences by Southern blot however, consumes much DNA and is not applicable to degraded DNA samples often recovered from body-fluid stains found at crime scenes. The polymerase chain reaction (PCR) technique may overcome these problems. With oligonucleotide primers flanking the repeat region, amplification of the VNTR alleles followed by direct visualization on ethidium bromide-stained agarose gels is possible. In those cases were the PCR yield is too low for direct visualization, the product can be blotted to a nylon membrane and hybridized with a labelled internal probe. Alternatively, the PCR product can be biotinylated during amplification and visualized by direct chemiluminescence after Southern transfer. The remarkable sensitivity of the PCR technique has allowed the detection of genetic polymorphisms in single cells, hair roots and single sperm. A drawback of this very high sensitivity however is that special precautions have to be taken to prevent accidental contamination resulting in erroneous interpretation of the results.